1. Field of the Invention
The present invention relates to a liquid ejecting apparatus, a recording apparatus, and a field generating unit. More particularly, the present invention relates to a liquid ejecting apparatus and a recording apparatus for attaching liquid discharged from an aperture of a nozzle plate mounted on a liquid ejecting head to a recording material, and a field generating unit capable of being used in these apparatuses.
2. Related Art
In a liquid ejecting apparatus, according to the demand for resolution improvement of a recording image, a droplet discharged from an aperture of a nozzle plate in a current liquid ejecting apparatus is miniaturized up to about several pl or pico-litter. Since such a minute droplet has extremely small mass, kinetic energy is rapidly lost by viscous resistances of an atmosphere once the droplet is discharged. Specifically, the speed of droplet becomes substantially zero, for example, when a droplet less than 3 pl flies a distance of about 3 mm in the atmosphere. Since a falling motion by acceleration of gravity and a viscous resistance force of an atmosphere are nearly balanced in a minute droplet of which kinetic energy is lost, it takes a long time to fall completely.
Moreover, in order to give larger kinetic energy to a droplet, it is also possible to raise jet velocity of liquid ejected from a liquid ejecting head. However, when actually increasing jet velocity from the nozzle plate, it is easy to produce an extremely minute droplet referred to as an ink mist when a droplet leaves the nozzle plate. Moreover, since viscous resistance of an atmosphere acting on each droplet becomes still larger, it is found that a travel distance of the droplet shortens rather than that of a droplet before increasing jet velocity.
A floating droplet produced as a result of various phenomena as described above is referred to as an aerosol, and floats in the vicinity of a traveling area of the liquid ejecting head. A part of aerosols floats up to an outside of the liquid ejecting apparatus, and thus adheres to the vicinity of the liquid ejecting apparatus to deface the apparatus. Moreover, most of aerosols adhere to each portion within the liquid ejecting apparatus before long. Particularly, when aerosols adhere on a carrying path of a recording material such as a platen, a recording material to be next carried is polluted. Moreover, when aerosols adhere to an electric circuit, a rotary scale, a linear scale, or various types of optical sensors of the liquid ejecting apparatus, this may cause malfunction of the apparatus. Furthermore, when a user touches a portion to which aerosols adhere, a hand of the user is polluted.
A liquid ejecting apparatus described in the following Japanese Patent Application Publication 2005-186290 forms an electric field between a nozzle plate and a matter to be processed to make Coulomb force facing the matter act on a droplet. In this way, it is described to make the droplet surely arrive at the matter to prevent the generation of aerosols. Moreover, Japanese Patent Application Publication 2005-186290 proposes that electrification of a matter to be processed caused by attaching the charged liquid to the matter is prevented by reversing the polarity of voltage to be applied to the matter.
However, the configuration disclosed in Japanese Patent Application Publication 2005-186290 includes, as essential components, a switching means for reversing the polarity of applied voltage, a control means for measuring a timing of switching, or the like, in addition to a voltage applying means for applying a voltage to a matter to be processed. Therefore, the magnitude and manufacturing cost of the liquid ejecting apparatus just have to be raised in order to realize a configuration as described in Japanese Patent Application Publication 2005-186290.